UP 1507 (GP40M-2) sits with other light power in the North Yard in Denver, Colorado.

Union Pacific 2-8-0 320 leads a westbound troop train with caboose near Denver Colorado in 1943. Otto Conrad Perry photo, from my collection.

D&RGW train 9 is leaving Denver Colorado in 1949. Otto Perry photo, from my collection.

RTD commuter train #4022 (Hyundai Eagle P3) heads towards Denver International Airport.

The Royal Gorge, D&RGW First #1, is departing Denver Colorado in 1957. Otto Conrad Perry photo, from my collection.

RTD commuter train 4028 (Hyundai Eagle P3) heads towards Denver International Airport as a United Airlines plane takes off.

The evening sun shines on the operations building in the Union Pacific's North Yard in Denver, Colorado.

Amtrak engine #78 (P42DC) races the snow clouds as it leads the Winter Park Express through the signal bridge in the Union Pacific's North Yard in Denver, Colorado.

UP 7459 (ES44AC) sits with other Union Pacific power in the large North Yard in Denver, Colorado.

Two Denver RTD commuter trains pass each other at Denver International Airport.

UP 1507 GP40M heads in from the yard after a day or sorting cars in the Union Pacific's North Yard.

RTD commuter train #4012 (Hyundai Eagle P3) heads towards Denver International Airport on the A-Line.

UP 801 (GP38-2) works sorting cars in the Union Pacific's North Yard in Denver, Colorado.

Planes, Trains, and Automobiles. The RTD Commuter Rail A-Line "Train to the Plane" runs towards the terminal at Denver International Airport just as a United Airline Boeing 737 takes ... (more)

UP 1826 (SD40N) works a cut of cars in the Union Pacific's North Yard in Denver, Colorado.